It is known to seal articles in pockets which are formed and sealed in plastic windows of paperboard blanks. These blanks have one or more openings which are covered, on one surface, by a heat-deformable and heat-sealable plastic sheet. The pockets are formed by heating the plastic material extending across the windows and deforming this plastic material to form a pocket. After the article is placed in the pocket, the pocket is closed, for example by folding the blank about a fold line and then heat sealing the plastic material. As the plastic sheet or film which is used is generally transparent, the article is provided in a decorative package in which it is sealed but nevertheless is fully visible.
However, while the known packaging machines for thus packaging articles in transparent pockets in a paperboard blank provide a satisfactory product, there has been a demand for a packaging apparatus, for forming such a product, which will be more efficient and have a much higher output per unit of time than machines and methods presently available.